Have you seen a photo of what tanks in combat look like these days? They have cages welded on top of them. Also the hatches can be closed. A lot of tankers like to have the hatch open so the commander can have have more visibility, but it's not a necessity.
There have been ways to take out a tank with missiles for a long time now. The reason why they're still used is that air defenses exist and nothing beats the cost efficiency of moving a big gun close to the enemy and firing a lot of cheap ammunition at them.
Also are you going to tell civilians they can move back into their towns based solely on drones? If the civilians are behind a bunch of tanks, they're safe because the drones will go after the tanks before going after the civilians. You need soldiers to hold ground. A soldier in a tank is going to be harder for a drone to kill than a soldier that's not in a tank.
Yes drones are effective, but drones can't hold ground and keep civilians safe.